beyce douglas



'(No Moaei.) A. D. B. DOUGLAS.

LINK MOTION FOR WORKING VALVES.

No. 336,844. Patented Feb. 23, 1886.

NITED STATES PATENT OFFICE.

AROHIBALD D. BRYCE DOUGLAS, OF SEAFIELD, ARDROSSAN, COUNTY OF AYR, SCOTLAND.

LINK-MOTION FOR WORKING VALVES.

SPECIFICATION forming part of Letters Patent No. 336,844, dated February 23, 1886.

Application filed September 8, 1885. Serial No. 176,517. (No model.) Patented in England July 4, 1885, No. 8,132.

To all whom it may concern.-

Be it known that I, AROHIBALD DOUGLAS BRYCE DOUGLAS, a subject of the Queen of Great Britain, residing at Seafield, Ardrossan, in the county of Ayr, Scotland, have invented a new and useful Link-Motion for \Vorking the Slides or Valves of Steam and Other Fluid- Pressure Engines, (for which I have made application for a Patent in Great Britain, dated July 4, 1885, No. 8,132,) of which the following is a specification.

My invention relates to the arrangement of levers and links for working the slides or valves of steam or other fluid pressure engines, to stop, start, reverse, or to vary expansion. rived from that of the piston-rod combined with a movement obtained from a single eccentric.

The levers and links which I employ may be variously arranged to suit the particular forms and conditions of the engines to which they are applied, as illustrated by the accom panying drawings, in which- Figure 1 is a side elevation of an engine embodying my invention, and Fig. 2 a diagram showing a modification of the invention.

In the accompanying drawings, where Fig. 1 shows an elevation of a stationary inverted engine, the numeral 1 indicates the beam pivoted at 2 to a bell-crank, 20, rocking on a fulcrum, 2], one end of the beam being connected to the piston-rod while the other is pivoted to the connecting-rod 5 of the slide-rod 6. The curved link 4 is mounted on fixed centers 3, and is movable into different positions by the gear 13 and 14. The rod 23 of the eccentric on the crank-shaft is pivoted to the end of the rod 22 sliding in the curved link, the other end of the rod 22 being pivoted to the bell-- crank 20.

Assuming the curved link to be held in the The motion for this purpose is de position in which its curvature is concentric to the joint at 20, then the eccentric, in moving the end of 22 backward and forward in the link, will not impart any motion to the bell-crank, and consequently the sliderod will receive a motion due only to that of the beam 1 resulting from its connection with the conmeeting-rod; but, according as the link 4 is SO made to assume a more or less eccentric position in one direction or the other relative to the joint 20, the to-and-fro movement of the rod 22 in the link will produce 2. corresponding rocking motion of the bell-crank, and con sequently of the fulcrum of the beam 1, whereby the movement of the slide-rod will be modified.

Fig. 2 shows a diagram of a modification, in which the parts are adapted for a horizon- 6o tal engine, the only difference being that instead of the rod 22 being connected to a bellcrank carrying the beam 1, this is directly pivoted to the end of the rod 22. The action is otherwise preciselythe same, as above de- 6 scribed.

Having thus described the nature of my invention and in what manner the same is to be performed, I claim- In combination, with the lever 1, oscillating on a movable fulcrum in time with the piston and linked to the valve-rod, the curved link 4, fitted with a sliding block which is linked to the fulcrum of the lever 1, and is caused to reciprocate along the link 4 by an eccentric,

substantially as described.

Intestimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 25th day of August, A. D. 1885. g

A. D. BRYCE DOUGLAS.

Witnesses:

JAMES SYME, ANDREW Lame. 

